jQuery.ketchup
.validation('alpha',
            'Must be alpha.',
            function(form, el, value) {
  return /^[a-z]+$/i.test(value);
})
.validation('alphanum',
            'Must be alphanumeric.',
            function(form, el, value) {
  return /^[a-z0-9]+$/i.test(value);
})
.validation('alphanum_extra',
            'Must be alphanumeric (and/or space, -, _)',
            function(form, el, value) {
  return /^[a-z0-9-_ ]+$/i.test(value);
})